Electronic ignition system

ABSTRACT

A solid state control unit for a high potential generating system which is connected in series with an impulse signal and coil to maximize coil charging time between discharges thereof by means which eliminates eratic impulses from affecting the system and includes means to adjust the timing of the impulses for maximum efficiency and performance.

nited States Patent 1191 Adams [451 Dec. 17,1974

Guy Adams, Monroe, NY.

[52] U.S. Cl.... 123/148 E, 123/146.5 A, 123/117 R [51] Int. Cl. F02p3/02, F02p 5/08 [58] Field of Search 123/148 E, 146.5 A, 117 R 3,605,7139/1971 LeMasters 123/148 E 3,651,341 3/1972 Shana 3,660,689 5/1972()ishi 1, 123/148 E Primary Examiner-Laurence M. Goodridge AssistantExaminer-Cort Flint Attorney, Agent, or Firm-Richard G. Geib 57 7ABSTRACT A solid state control unit for a high potential generatingsystem which is connected in series with an impulse signal and coil tomaximize coil charging time [56] References Clted between dischargesthereof by means which eliminates UNITED STATES PATENTS eratic impulsesfrom affecting the system and includes 3,202,146 8/1965 Short et a1 1.123/148 E means to adjust the timing of the impulses for maxi- 3,3l4,4074/1967 Schneider 123/148 E mum efficiency and performance 3,521,6117/1970 Finch 123/148 E 3,587,551 6/1971 Harrow 123/148 E 10 Claims, 8Drawing Figures /4 32 34 m) f 30 X6) 2 e 2 2g /2 i" ELECTRONIC IGNITIONSYSTEM BACKGROUND OF INVENTION Ignition systems for internal combustionengines operate, as is well known, on the principle of stored inductiveenergy transfer. In such systems presently employed and proposed animpulse signal is generated by mechanical contacts, magnetic means andphotosensitive devices to provide and interrupt current flow to acircuit connected to an ignition coils primary winding. The providing ofthe current is known as the charging of the coil and the interruption ofsame permits the coil to discharge whereby a spark plug is energized toinitiate combustion in an engine cylinder. Various types oftransistorized circuits have been proposed whereby the charging anddischarging aforesaid is controlled by the transistor circuit in seriesconnection with the signal generating means and the coil. his to theimprovement of these and other similar prior art systems that thepresent invention is directed whereby the time required to charge a coilis maximized to provide a higher output potential which man engineignition system, for example. provides easier-engine starts and stableoperation at higher speeds than is now possible by any prior art systemsknown.

It is a more particular object of this invention to provide a new andimproved semiconductor control system that if employed with an ignitionsystem has the capability of eliminating all but a triggering electricalimpulse, the capability of varying the lead-lag of the triggeringelectrical impulse and the capability of fixed pulse width ignition coildischarge where'by longer coil charging time is possible at everyconceivable engine speed.

A still more particular object of this invention is to delay the outputsignal'of a signal generator, amplify it, convert it into a square wavesignal, differentiate it thereafter, direct it through a one-shotmonostable network, amplify it and gate it in the control of anelectrical device such as an engine ignition coil.

DRAWING DESCRIPTION FIG. 1 is a block diagram of an electronic ignitionsystem employing the principals of this invention.

FIGS. 2 through 7 are illustrations of the electrical wave forms thatwill result at various points in the electronic ignition systemaccording to this invention.

FIG. 8 is schematic diagram of the electronic control system accordingto a preferred form of this invention in series connection with theimpulse generating means and the coil.

DETAILED DESCRIPTION In reference to FIG. I there is shown a set ofconventional ignition points 10 operable by a cam means 12 as is wellknown in the prior art. An electrical impulse generated by the points 10is applied to an RC cornering network 14 whereby the effect of pointdither or bounce is smoothed. Next the impulse is directed to a variableresistance network whereby one can advance or retard the impulse appliedto an amplifier 18. The amplified impulse is then supplied to a Schmidttrigger to drive same to produce an output delivered to differentiationnetwork 22 which then generates a sharp pulse driving a one-shotmonostable network 24. The output of network 24 is then delivered to anamplification and electronic switching network 26 which then drives coilswitching network 28 that is in control of the charging of primarywinding 30 or the curtailment of same. This will, as is readilyappreciated by those skilled in the art, in the first instance create amagnetic field in coil 32 when the coil is charging and a collapse ofsame when curtailed to induce a high ignition potential in secondarywinding 34 that is supplied to spark plugs 36, for example, causing themto spark.

It is thus realized'that an electrical square wave form 38 provided bythe points 10, as seen by FIG. 2, is changed to a sloping waveform 40illustrated in FIG. 3 which is generated by the RC corneringnetwork 14.Electrical wave form 40 has a triggering position 42 which is variableby means of network 1 6 for operation of Schmidt trigger network 20 torestore a square wave form 44 displaced in time. The differentiationnetwork 22 then provides a sharp narrow triggering pulse wave form ofpositive and negative spikes 46 and 48 which are provided to theone-shot monostable network 24. This generates a gate waveform 50, asseen by FIG. 6 whose sign is corrected by the'network 26 to provide thewave form 52 of FIG; 7. As is obvious from a comparison of FIGS. 2through 7 the duration of the pulse shown by wave form 52 no longer hasthe broad pulse width or position as the initiating square wave form 38.In that the pulse provided by wave form 52 controls the time the primarycoil 32 current is interrupted it is possible to increase the chargingtime for the primary coil 32.

In order to effectuate this advantageous operation .a semiconductorcircuit is now to be described in re-ference to FIG. 8. Ignition points10 are shown connected via an ignition switch 54 to a battery 56 andground .58 by means of resistor 60 in lead 62 and lead 64, respectively.Zener diode 66 in lead 68 connects the ground potential to lead 62 tomaintain constant voltage at junction 70. Opening and closing of points10 produces an electrical impulse for the RC cornering network comprisedof resistor 72 and capacitor 74. This network in a preferred embodiment,creates a 400 psec delay so that the electrical impulse is smoothed andzener diode 66 maintains the constant voltage. This is fed to variableresistor 76 whose sliding contact 78 is connected by lead 80 to acapacitor 82 which is tapped at 84 by lead 86. A discharge diode 88 isconnected at juncture 90 to lead 68 between the zener diode 66 andjuncture 70. Therefore, an impulse from the points 10 of a square waveform is converted to a slopping or ramp wave form by the RC corneringnetwork of resistor 72 and capacitor 74 having a predetermined delaywith a constant voltage as maintained by the zener diode 66 which bymeans of resistor slider 78 provides an output voltage no more than andnormally less than the aforementioned constant voltage. This output isthen connected by conductor 90 to the base of an emitter-followeramplifier shown schematically as at 92 having a collector 94 connectedby conductors 96 and 98 to resistor 100 connected to the positiveconductor 102 from ignition switch 54. Resistor 100 is connected tonegative conductor 104 by conductor 106 and zener diode 108. Theamplifier circuit is completed by connecting conductors 102 and 104 by aconductor 110 having a reverse transient protection diode 112 wherebythe amplifier 92 is triggered to amplify the pulse from variableresistor 66 whereby an output is provided at emitter 114 and fed byconductor I16 to base 118 of transistor 120 of the Schmidt triggercircuit 20. As is familiar to those skilled in the art, transistors 120and 136 are interposed between conductors 98 and 104. Transistor 120 hasits collector 128 connected to such circuit and its emitter 130connected by a conductor 132 to emitter 134 of a transistor 136 whosecollector 138 is connected to resistor 140 and thence conductor 98. Aconductor 140 connects resistor 124 to base 142 of transistor 136. TheSchmidt trigger circuit is completed then by providing resistor 146between conductors 132 and 104. It may therefore be realized that apositive input pulse provided to base118 of transistor 120 must be of asufficient level to overcome the reverse bias provided by resistor 146,and when of a sufficient level it applies a forward bias makingtransistor 120 conductive developing a voltage drop across resistor 122decreasing the positive potential across base 142 of transitor 136 untiltransistor 136 stops conducting at which point there is no voltage dropacross resistor 140 and the potential in collector 138 equals that inconductor 98, and an output signal is formed for the duration of theinput pulse. Therefore, a square wave 44 is created displaced in time inrelation to the point 42 on the ramp wave 40. This drives capacitor .148providing a spike 46, controlled by resistor 150 to a predetermined timeduration, which is found at juncture 152. A steering diode 155 isconnected to juncture 152 and a conductor 154 connects it to emitter 156of transistor 158 whose base is connected to conductor 160 betweencapacitor 162 and resistor 164 respectively connected to conductors 104and 98. Conductor 166 taps into conductor 154 at juncture 168 and leadsto emitter 170 of transistor 172. Collector 174 of transistor 158 isconnected via resistors 176 conductor 98 and resistor 178 to collector180 of transistor 172. A capacitor 182 in conductor 184 connectscollector 174 to base 186 of transistor 170, and a shunt diode 188 isconnected between conductor 166 and base 186 between same and capacitor182. In such circuitry, as this one-shot monostable network 24, thetriggering signal, i.e.. spike wave form 46, induces a transition from astable state to a quasi stable state for a time on the order of 400 usecwhich automatically returns to the stable state thereafter while at thesame time generating the rectangular wave form 50 whose beginning andend are marked by abrupt discontinuity in voltage waveform. Thetriggering spike 46 drives capacitor 162 and is introduced to base 190where it affects only transistor 158 of this network 24, so as to notload the circuit. The time of the quasi stable state is controlledthrough resistor 176 when transistor 158 is conducting. At the same timethe resistance on emitter 156 is substantial enough to stabilizeresistor 176 whereby the time that transistor 158 is conducting is alinear function of the input to the base. This output is provided to thediode coupler 192 and resistor 194, connected to conductor 104, atjuncture 196. Emitter follower amplifier 198 is connected to juncture196 and via resistor 200 to switching transistor 202 to provide anoutput to terminal 204 equal but opposite in sign to that at juncture196, as illustrated by rectangular wave form of FIG. 7. Such a pulse, asis possible at terminal 204, is used to drive ignition coil switchingnetwork comprised of resistance 206 between conductor 102 and lead 208intermediate of the connection of this lead with base 210 of transistor212. Emitter 214 is connected by leads 216 and 217 to conductor 104 viaterminal 204 and collector 218 is connected by resistor 220 to conductor221 connected to conductor 102 via terminal 204. Collector 218 is alsoconnected to blocking diode 222 connected by conductor 224 to base 226of switching transistor 228 whose emitter 229. is connected to conductor230 leading to conductor 217 and via terminal 204 to ground 58.Collector 232 of transistor 228 is connected to one end of primarywinding 30 connected at its other end to conductor 221. Zener diodes 234and 236 shunt emitter 229 to the output of collector 232. Therefore. itshould be readily appreciated that if no pulse is available at terminal204 then transistor 212 is off and current is being driven through diode222 to base 226 of transistor 228 causing it to conduct. This willproduce current in primary winding 30 charging the coil 32. However,when a pulse such as rectangular wave form 52 provided by network 26 isprovided to network 28 and particularly base 210 of transistor 212whereby it becomes conductive (saturated), transistor 228 is cutoff andcurrent ceases to be directed to primary winding 30 and a high ignitionpotential is created in the secondary winding 34 which in the case of anengine ignition system is used to cause arcing across contacts of sparkplug 36.

lt will be apparent that the system described and illustrated in theaccompanying drawings should be considered as illustrative of how suchan electronic ignition system can be applied to present day engineignition systems employing contact points, and that it is equallyapplicable and beneficial to other impulse generating systems forcontrolling engine ignition as are known. In addition, it will beapparent that the utility of this invention is of broader applicationthan just in engine ignition system as it is readily adaptable to anysystem needing lead-lag pulse shaping. Further, the scope of thisinvention is considered to embrace structure equivalent to thatdisclosed now and hereafter either from a mechanical point of view orfrom an electronic one without departing from the spirit of the intentof disclosure in return for these Letters Patent.

What is claimed is: I 1. An engine ignition system comprising: anelectrical source; first means connected to said source and operable inresponse to engine operation for generating an impulse signal ofpredetermined time duration; second means connected to said first meansfor receipt of said impulse signal and operable to change a squarewaveform of said impulse signal to a nonlinear sloping waveform for saidtime duration of said impulse signal. said non-linear sloping waveformof said second means terminating upon termination of said squarewaveform of said impulse signal; third means operatively connected tosaid second means to vary the gradient of said non-linear slopingwaveform within the time duration of said square waveform of saidimpulse signal to provide a faster or delayed rise of the non-linearsloping waveform from said second means whereby control of the positionof a triggering potential therefrom is possible for proper timing of theengine ignition system; fourth means connected to said third means andenergized by the triggering potential to generate a signal within thetime duration of said impulse signal and displaced in time from theinception of said impulse signal in accordance with the triggeringpotential on the non-linear sloping waveform to be of a duration of timewithin said predetermined time duration of said impulse signal of saidfirst means;

fifth means connected to said fourth means providing a switching signalwithin said time duration of said impulse signal of said first means;

an ignition coil connected to said electrical source and switching meanswhereby charging of a primary winding of said coil is controlled by saidswitching means to control transmission of a high energy potential froma secondary winding of said I coil within said time durationof saidimpulse signal; and

spark plug means connected to said coil to be activated by said highenergy potential to provide engine ignition.

2. The structure of claim 1 wherein said second means is characterizedas a RC cornering network including means to clamp a constant voltage ofa square wave form.

3. The structure of claim 2 and further characterized by said thirdmeans including a variable resistor connected to said RC corneringnetwork.

4. The structure of claim 3 wherein said variable resistors slidingcontact is connected across said first means by a capacitor anddischarge diode.

5. The structure of claim 4 wherein said fourth means is characterizedas a means to re-shape said signal from said third means displaced intime and of a lesser predetermined duration whereby charging of saidprimary winding is permitted to take place for a substantial constantperiod of time regardless of fluctuations of said impulse signal.

6. The structure of claim 1 wherein said second means is furthercharactirized as an RC cornering network including means to maintainconstant voltage.

7. The structure of claim 1 wherein said third means to vary thegradient of said slope to control the position of a triggering potentialincludes a variable resistor connected by a capacitor and dischargediode to said second means that changes a squarewave form signal fromsaid first means to said non-linear sloping waveform along which saidtriggering potential is located.

8. The structure of claim 6 wherein said means to vary a triggeringpotential includes a resistor connected to said RC network; and

a sliding contact for varying the output of said resistor, said slidingcontact being connected by a discharge diode to the constant voltageoutput of said RC cornering network and by a capacitor to said networkin advance of the means therein to maintain constant voltage.

9. The structure of claim 1 wherein said fourth means connected to saidthird means tovary the gradient of said slope of said sloping characterwaveform to advance or retard the time to reach said triggeringpotential includes:

A Schmidt trigger;

A differentiation network 'operably connected to said Schmidt trigger; Aone-shot monostable network connected to said diferentiation network;and An amplification and electronic switching means connected to saidone-shot monostable network. 10. The structure of claim 9 wherein saidfourth means generates an impulse signal of square wave form similar tobut displaced in time and of lesser duration than a square waveform fromsaid first means before decay; said fifth means connected to said fourthmeans comprises an electronic switching means including normallyconducting and non-conducting transistors for controlling said ignitioncoil; and shunt means connected between said electronic switching meansand said ignition coil protecting said electronic switching

1. An engine ignition system comprising: an electrical source; firstmeans connected to said source and operable in response to engineoperation for generating an impulse signal of predetermined timeduration; second means connected to said first means for receipt of saidimpulse signal and operable to change a square waveform of said impulsesignal to a non-linear sloping waveform for said time duration of saidimpulse signal, said non-linear sloping waveform of said second meansterminating upon termination of said square waveform of said impulsesignal; third means operatively connected to said second means to varythe gradient of said non-linear sloping waveform within the timeduration of said square waveform of said impulse signal to provide afaster or delayed rise of the non-linear sloping waveform from saidsecond means whereby control of the position of a triggering potentialtherefrom is possible for proper timing of the engine ignition system;fourth means connected to said third means and energized by thetriggering potential to generate a signal within the time duration ofsaid impulse signal and displaced in time from the inception of saidimpulse signal in accordance with the triggering potential on thenon-linear sloping waveform to be of a duration of time within saidpredetermined time duration of said impulse signal of said first means;fifth means connected to said fourth means providing a switching signalwithin said time duration of said impulse signal of said first means; anignition coil connected to said electrical source and switching meanswhereby charging of a primary winding of said coil is controlled by saidswitching means to control transmission of a high energy potential froma secondary winding of said coil within said time duration of saidimpulse signal; and spark plug means connected to said coil to beactivated by said high energy potential to provide engine ignition. 2.The structure of claim 1 wherein said second means is characterized as aRC cornering network including means to clamp a constant voltage of asquare wave form.
 3. The structure of claim 2 and further characterizedby said third means including a variable resistor connected to said RCcornering network.
 4. The structure of claim 3 wherein said variableresistor''s sliding contact is connected across said first means by acapacitor and discharge diode.
 5. The structure of claim 4 wherein saidfOurth means is characterized as a means to re-shape said signal fromsaid third means displaced in time and of a lesser predeterminedduration whereby charging of said primary winding is permitted to takeplace for a substantial constant period of time regardless offluctuations of said impulse signal.
 6. The structure of claim 1 whereinsaid second means is further charactirized as an RC cornering networkincluding means to maintain constant voltage.
 7. The structure of claim1 wherein said third means to vary the gradient of said slope to controlthe position of a triggering potential includes a variable resistorconnected by a capacitor and discharge diode to said second means thatchanges a squarewave form signal from said first means to saidnon-linear sloping waveform along which said triggering potential islocated.
 8. The structure of claim 6 wherein said means to vary atriggering potential includes a resistor connected to said RC network;and a sliding contact for varying the output of said resistor, saidsliding contact being connected by a discharge diode to the constantvoltage output of said RC cornering network and by a capacitor to saidnetwork in advance of the means therein to maintain constant voltage. 9.The structure of claim 1 wherein said fourth means connected to saidthird means to vary the gradient of said slope of said sloping characterwaveform to advance or retard the time to reach said triggeringpotential includes: A Schmidt trigger; A differentiation networkoperably connected to said Schmidt trigger; A one-shot monostablenetwork connected to said diferentiation network; and An amplificationand electronic switching means connected to said one-shot monostablenetwork.
 10. The structure of claim 9 wherein said fourth meansgenerates an impulse signal of square wave form similar to but displacedin time and of lesser duration than a square waveform from said firstmeans before decay; said fifth means connected to said fourth meanscomprises an electronic switching means including normally conductingand non-conducting transistors for controlling said ignition coil; andshunt means connected between said electronic switching means and saidignition coil protecting said electronic switching means.